How did Pavlovian conditioning differ from B.F. Skinner’s operant conditioning?

Pavlovian conditioning (also known as classical or respondent conditioning) and B.F. Skinner’s operant conditioning differ primarily in the nature of the behavior and the role of the subject’s actions.12

• Nature of Response: Pavlovian conditioning involves involuntary, reflexive responses, such as a dog’s salivation in response to a bell. In contrast, operant conditioning involves voluntary behaviors—actions the subject chooses to perform to achieve a specific result, such as a rat pressing a lever to receive food.23
• Contingency: In Pavlovian conditioning, the response is elicited by a stimulus that has been associated with a biologically significant event (the unconditioned stimulus). In operant conditioning, the behavior is contingent upon the subject's own actions; reinforcement occurs only after the organism executes a predesignated behavioral act.12
• Mechanism: Pavlovian conditioning relies on the association between two stimuli. Operant conditioning relies on the consequences of behavior, where the subject learns that specific actions lead to rewards or the avoidance of punishment.132

While both processes are forms of associative learning that result in behavioral change, they represent distinct ways in which organisms adapt to their environments.13